A measurement of the partial width ratio Γbb Γhad using a method which tags the Z → bb decays through the lif etime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both Γbb Γhad and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of Γbb Γhad = 0.2192±0.0026(stat.)±0.0016(Γcc/ Γhad) is found. Combining this result with other recent ALEPH Γbb Γhad measurements gives a 95% confidence upper limit on the Standard Model top mass of Mt < 228 GeV.

Buskulic, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J., et al. (1993). A precise measurement of ΓZ→bb/ΓZ→hadrons. PHYSICS LETTERS. SECTION B, 313(3-4), 535-548 [10.1016/0370-2693(93)90028-G].

A precise measurement of ΓZ→bb/ΓZ→hadrons

CARPINELLI, Massimo;
1993

Abstract

A measurement of the partial width ratio Γbb Γhad using a method which tags the Z → bb decays through the lif etime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both Γbb Γhad and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of Γbb Γhad = 0.2192±0.0026(stat.)±0.0016(Γcc/ Γhad) is found. Combining this result with other recent ALEPH Γbb Γhad measurements gives a 95% confidence upper limit on the Standard Model top mass of Mt < 228 GeV.
Articolo in rivista - Articolo scientifico
Physics
English
1993
313
3-4
535
548
none
Buskulic, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J., et al. (1993). A precise measurement of ΓZ→bb/ΓZ→hadrons. PHYSICS LETTERS. SECTION B, 313(3-4), 535-548 [10.1016/0370-2693(93)90028-G].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/390416
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